1. Field of the Invention
The present invention relates to the anchoring of ligament replacements or soft tissue in bone tunnels, and more particularly to a method for locating and installing a transverse pin for holding a ligament replacement in a tunnel with the pin intersecting the tunnel and the ligament replacement. In the replacement of an anterior cruciate ligament (ACL), for example, a tunnel is drilled upwardly through the tibia plateau upwardly into the distal end of the femur. Typically, the tunnel entry point is the anterior portion of the tibia below the tibia plateau. These tunnels are typically located initially by inserting or drilling a guide pin, commonly called a K-wire, upwardly into the tibia and then upwardly into the femur while the tibia and femur are held in a desired and appropriate location to accommodate an ACL replacement. The tunnel is essentially located so that the replacement ligament is in a position to function as the replaced ACL. The K-wire or guide pin is used because it is small diameter and the surgeon can inspect the location of the K-wire and reinsert it if it is not well located without damaging the bone structure to any significant extent. It will be appreciated that the position of the K-wire may be inspected by arthroscopic techniques as well as by X-ray or other imaging approaches.
Also, typically, once the K-wire is properly positioned, a cannulated drill, sometimes referred to as a drill/reamer, is placed over the K-wire and driven upwardly to form the tunnel using the K-wire as the guide for the drill.
The method of the present invention utilizes the drill which forms the tunnel while it is in the tunnel as the control member for locating and installing the transverse pin for holding the ligament replacement in the tunnel within the femur. Specifically, within the method of the present invention, a drill guide is installed on the drill used in the tunnel drilling step, the drill guide being selectively rotatable about the axes of the drill and the guide pin and also selectively longitudinally movable along the axis of the drill appropriately to position the drill guide.
The method of the present invention contemplates installing such a transverse pin from a point outside the femur to extend transversely inwardly to the tunnel in the femur and to intersect the tunnel and the ligament replacement inserted therein.
2. The Prior Art
The prior art includes several different types of drill guides for forming tunnels in the femur and tibia for anchoring ligament replacements. One example is U.S. Pat. No. 4,901,711 which shows such a drill guide which mounts on the K-wire after it is inserted into the knee joint. The K-wire exits the knee joint at a point below the tibia and at another point above the femur. The drill guide of the '711 patent is journalled on the K-wire so that the guide is rotatable about the axis of the K-wire. The guide then has a drill sleeve which moves longitudinally parallel to the axis of the K-wire to a selected point to locate a transverse anchoring pin. The method of the present invention is an improvement over the method shown in the '711 patent because the guide is mounted only below the tibia plateau on the shank of the tunnel drill and, of course, the tunnel itself is drilled before the guide used. Using the method of the present invention, the tunnel may be located and drilled upwardly to a point terminating the tunnel in the femur at a preselected point. This preselected point is established on the drill itself such that the drill guide, when mounted on the drill, and moved to an appropriate scale point on the drill, will locate the transverse pin at an appropriate location below the uppermost end of the tunnel.
Another example is U.S. Pat. No. 4,985,032 which shows a drill guide for locating transverse pins for holding ligaments in tunnels formed in knee joints, particularly to replace the ACL. The U-shaped guide of the '032 patent is used with one leg of the guide inserted upwardly through the tunnel after the drill is removed. Use of the U-shaped guide of the '032 patent requires extra steps which are eliminated by using the tunnel drill itself as a mount for the drill guide. The tunnel drill of the present invention is provided with scale means so that the surgeon will know exactly where the uppermost end of the drill and tunnel are and where the transverse pin has to be located in the femur properly to intersect any ligament replacement placed in the tunnel and pulled upwardly to that innermost end.